Simianus
, , , , , , , , , , | abbreviation = Sim | genitive = Simiani | pronounce = Name: /'sim•ē•yon•is/ Genitive: /'sim•ē•yon•ē/ | symbolism = the | dinoname = Jamaudij | dinoabbrev = Jam | dinogen = Jamauda | dinopronounce = Name: /'jam•ä•dij/ Genitive: /'jam•ä•dä/ | mRA = | mdec= | ndec = | sdec = | wRA = | eRA = | quadrant = SQ3 | bordering = Felis Malus Noctua Solarium Tarandus | area = 2962.656 sq. deg. (9 ) | proportion = 71.817‰ | average = 269.332 sq. deg. (10 ) | namedstars = 18 | mainstars = 7 | nakedeyestars = 528 | bfstars = 565 | ehstars = 43 | brightstars = 36 | brighteststar = (−0.01 }}) | nearbystars = 16 | neareststar = (1.30 , 4.24 ) | messierobjects = 4 | fullrange = 6°N–90°S | partialrange = 81°N–6°N | date = April 11 | solarzodiac = 11/23–11/30 | tropicalzodiac = 10/23–11/23 | siderealzodiac = 11/16–12/16 }} Simianus (Latin for ) is a caelregio with midpoint located in the third of the . The and the cross this caelregio. Simianus covers about 72‰ of the sky with an area of 2963 square degrees, making it the third smallest caelregio after Selachimorphus and Malus. Simianus is divided into eleven s (the list is at the top of the infobox to the right), including three famous constellations: , , and . Simianus contains the nearest star system to Earth as well as the , which is the most recognizable in the southern sky. This caelregio also contains few recognizable doubles and multiples, as well as a couple of famous s. Former name Vexilius the was the former name for Simianus until December 2010. Notable stars Bright stars At a of −0.01, a is the Simianus' brightest star and is also the fourth brightest overall, located in Centaurus. The other notable bright stars in Simianus are * –– a 0.60 located in Centaurus, * –– a 0.87 B-type main sequence located in Crux. Acrux is the southernmost first magnitude star of the sky; * –– a 0.96 located in Scorpius. Antares is one of the four brightest stars near the , the others are in Noctua, in Felis, and in Araneus; * –– a 1.30 B-type located in Crux; * –– a 1.63 located in Crux; * –– a 1.86 located in Scorpius; * –– a 1.93 giant located in ); and * –– a 2.78 B-type subgiant located in Crux. Variable stars In Scorpius, the is an unique star that it turns on and off caused by inclination changes by the gravity of a tertiary star. Antares is a type LC star varying between 0.88 and 1.16 in magnitude. Multiple stars Alpha Centauri is a tertiary star system. It composes of G-type, K-type, and M-type stars. The M-type star is a nearest star to the Sun at a of 4.24 s. The separation between components A and B ranges from 11.2 to 35.6 AU with an orbital period of 79.91 years. Proxima Centauri orbits the binary at a distance of 13,000 AU with a period between 100,000 to 500,000 years. Despite that closest approach in binary system, the s (region around the star where liquid water is stable on the planet's surface) around both stars should be stable. Another notable star system is Acrux, which is a composing of α and α Crucis. One of the pair α is a with a period of 76 days at a separation of about 1 AU. The binary period is at least 1500 years at a minimum distance of 430 AU, and may be much longer. Another nearby companion α Crucis at 90 s away from the binary pair may be just an optical closeness but not gravitationally bound. The suggest that α is moving further away from the main binary pair. α may be twice as distant as the main binary pair. Double stars There is the in Scorpius: . Zeta 1 is a while Zeta 2 is an and is the brighter of the pair, thus Zeta 1 is 19.5 times more distant than Zeta 2, 2573 vs. 132 light-years. Zeta 1 is a member of the open cluster . Another double star is in Centaurus. This can be resolved using just the with the separation of 0.66°, a bit more separated than the of the . ξ is twice as distant as ξ , 467 vs. 221 light-years. Solar twin The most known is , located in Scorpius. 18 Scorpii is similar to the Sun in terms of mass, radius, temperature, luminosity, metallicity, age, rotation period, and spectral type. The prospects for are very good. I spectulate that 18 Scorpii has 11 planets, three more than our Sun, including a forest planet located in its . Planetary systems As of September 3, 2011, there are 43 known s in Simianus. The notable example is (P1 Sim) in Scorpius which contains the oldest known planet at 12.7 billion years old that survived the explosion. This planet, named (P11), orbits at a distance of 23 AU, placing between the orbits of and in the . Another notable planetary system is (P4 Sim) in , which has four planets with the innermost is a midplanet and the outer three are mid-Jupiters. In Centaurus, (P11 Sim) is the first known to have a planet (named (P115)) which has mass 4.22 }} and orbits at a distance of 41 (41 × Earth–Sun distance). Notable deep sky objects Simianus contains two famous s: ( 7) in Scorpius and ( 5139, 80) in Centaurus. Crux contains the (NGC 4755), which is an . In Scorpius, there is the less famous globular cluster . This was the first globular cluster to have its stars resolved and is competing with in Ara for the nearest globular clusters to the Solar System. In Ara, there is the open cluster (also known as the Ara Cluster) visible to a large . This cluster contains a lot of massive, blue stars including some 24 s. In fact, it is the most compact young not just in the but the entire of galaxies. In , there is the (NGC 6087, C89), which is a open cluster with the variable star being the brightest member. Scorpius contains the : the (NGC 6302, C69); and it also contains the (NGC 6357), which is a , which contains the open cluster composed mainly of massive stars. Centaurus contains the (also known as the Bow Tie Nebula), which is a . In this nebula, the temperature is only one kelvin above , which is the coldest known place in the . Also in this constellation, there the . In Norma, there is the bipolar nebula . This nebula glows red caused by the ultraviolet radiation from the massive central star ionizing hydrogen gas. This nebula is shaped by the star's magnetic field and fast rotation. Yet another interesting nebula in Centaurus is the ( 2948), which is a where new stars form. Embedded within the nebula made of glowing reddish cloud of gas is the energetic young star cluster . Also in this constellation, there is the open cluster and emission nebula (also called the Lambda Centauri Nebula) (IC 2944, C100) featuring s called with sites of active star formation. Crux contains the (C99), which is a . Coalsack is the largest dark in the sky. It masses 3500 Suns and stretches dozens of light-years. In Scorpius, the (NGC 6334), which is a red-colored emission nebula caused by ionized hydrogen, can be seen using a small telescope. The (MyCn 18) is a planetary nebula located in . The ( ) is a planetary nebula located in . Also in Scorpius, there is the , which is a complex. The blue star marking the eye is the multiple star system . This complex includes the prominent blue reflection nebula . , which is an unique , and (NGC 5128, C77), which is a or with unusual dust lane, can be found in Centaurus. It is the only galaxy with opposite rotations between inner and outer arms relative to the observer. Gallery Visibility In the northern hemisphere, Simianus can be visible from late winter till the dawn of summer. About half of this caelregio can be visible from mid-northern latitudes but all of it can only be visible from very low northern latitudes and in the southern hemisphere. For the Southern Cross (Crux) and the nearest star (α Cen) to be seen, it can only be viewed from south of 35°N, that means that the Southern Cross and α Cen would never be visible from places like Europe, north and central Asia, and northern half of North America. The Southern Cross is useful for to southern observers because it points to the south especially when the bright south pole star is not present unlike the bright north pole star located in Avis. Zodiac As of 2011, the appears to briefly cross Simianus from November 23 till November 30: it crosses the only constellation . This al caelregio is located between Noctua to the west and Tarandus to the east. Category:Articles Category:Caelregios